Braking system for high acceleration operated free pistons

ABSTRACT

A braking system for high acceleration operated free pistons comprises a cylinder having one end with an inturned flange which provides a stop or abutment for a deformable shell in the form of a cylinder which is opened at each end. The piston, which is freely movable in the cylinder in a direction toward the shell is provided with a concave face on the side facing toward the shell and with a rim which engages behind an inwardly turned rim of the braking shell. The shell is deformed inwardly into the concave recess of the forward end of the free piston upon the impact of the piston against the shell and the deformation of the shell provides a shock absorption for the impact of the piston.

United States Patent 1 Zeyher 1 Oct. 2, 1973 1 BRAKING SYSTEM FOR HIGH3,272,896 9/1966 Winchester, Jr 425 392 x ACCELERATION OPERATED FREE3,396,636 8/1968 Bade 92/85 X 3,496,840 2 1970 Wandel ct al 92/85PISTONS Inventor: Fritz Zeyher, Ottobrunn near Munich, GermanyMesserschmitt-Bolkow-Blohm GmbI-l, Ottobrunn near Munich, Germany Filed:Mar. 13, 1972 Appl. No.1 233,909

Assignee:

Foreign Application Priority Data Apr. 1, 1971 Germany P 21 15 770.0

References Cited UNITED STATES PATENTS l/1958 Jacobus 92/85 X PrimaryExaminer-Martin P. Schwadron Assistant Examiner-Abe HershkovitzAttorney-John J. McGlew et a1.

[57] ABSTRACT A braking system for high acceleration operated freepistons comprises a cylinder having one end with an inturned flangewhich provides a stop or abutment for a deformable shell in the form ofa cylinder which is opened at each end. The piston, which is freelymovable in the cylinder in a direction toward the shell is provided witha concave face on the side facing toward the shell and with a rim whichengages behind an in wardly turned rim of the braking shell. The shellis deformed inwardly into the concave recess of the forward end of thefree piston upon the impact of the piston against the shell and thedeformation of the shell provides a shock absorption for the impact ofthe piston.

4 Claims, 2 Drawing Figures PATENTEDUBT 2l975 3.762279 BRAKING SYSTEMFOR HIGH ACCELERATION OPERATED FREE PISTONS BACKGROUND OF THEINVENTION 1. Field of the Invention This invention relates in general todeceleration devices and, in particular, to a new and useful device forbraking the high acceleration of a freely movable piston particularly ofa piston used in an antitank grenade launcher.

Deceleration of high-acceleration free pistons, such as pistons used inantitank grenade launchers or the like, is achieved by different means.In accordance with general design principles, the free pistons which aredriven by explosive, magnetic or othe forces, are accommodated in pairsin a cylindrical tube and are accelerated from the center of this tubein opposite directions. One of the two pistons may, for instance, ejecta projectile on the one side, while the other piston may accelerate aso-called counter mass. The resulting discharge is substantially freefrom recoil. The projectile caliber or counter mass caliber and itscross-sectional discharge clearance should approach, as closely aspossible, the internal diameter of the cylindrical tube (Caliber) sothat the dimensions may be kept as small as possible. During theacceleration process, the two ends of the cylindrical tube should beclosed by the two free pistons so as to prevent explosion flames andpowder gases escaping. Furthermore, in most instances, soundless(muffling) or almost soundless operation is desired. 2. Description ofthe Prior Art In another known arrangement, a braking or decelerationsystem includes a driving plate serving as the piston which is sloweddown by means of material deformation after performing the stroke andfor this purpose it is provided with a suitable creasing or deformationarea. Alternatively, the component (braking ring) against which thedriving plate or piston runs, can become deformed or, the chaser teethprovided thereon may be shorn off or the travel end may be conicallytapered.

In order to effect energy dissipation, it is necessary that thecomponents contributing to these systems are of large dimensions, orelse long brake paths have to be accepted. In the first case, anadditional requirement is the disproportionately strong reduction of theactual projectile caliber by comparison with that of the cylinder.

SUMMARY OF THE INVENTION In accordance with the invention, thedisadvantages of the known systems are avoided by providing a deformableshell, for example, of a plastic material, and preferably in the form ofa cylindrical tube, which is secured in the end of the cylinder towardwhich the free piston is movable. The cylinder is advantageouslyprovided with an inturned flange or collar which forms a stop orabutment which prevents the outward movement of the deformablecylindrical tube at this end of the cylinder. With the inventiveconstruction, the freely movable piston is provided with a concave endface on the end facing the deformable cylindrical tube and its cornersare sized to engage behind a bevelled rim of the deformable cylindricaltube. The bevel or chamfer is of a form such ,as to cooperate with theconcave end of the free piston so that impact movement of the pistonagainst the cylindrical tube causes an inward deformation of the wallsof the tube and an absorption of the impact shock.

Contrary to the systems of the art of record, the ac tion of the freepiston in this arrangement does not bring about an expanding deformationof the brake shell, but it has a crushing and shrinking effect upon thebrake shell deforming it so as to reduce its original diameter.Consequently, the wall thickness of the brake shell can be of very smalldimension so that the aforementioned differences in caliber betweenprojectile and projectile counter mass, on the one hand, and thecylinder on the other hand, are very small.

A further advantage of the inventive construction is the fact that thefrictional forces obtained during the deformation process between thebrake shell and the piston base settle on an area of the brake shellwhich enlarges inwardly in a substantially concentric manner. The resultis an even distribution of stress upon the piston base which in turnfacilitates its design.

An additional advantage obtained in this arrangement is that the actuallength of the brake path is extraordinarly short because the negativeacceleration curve has a strongly progressive effect, which has to beconsidered another essential factor in favor of the de sired weightreduction to be achieved. This braking characteristic is controllable incertain areas, particularly by the geometrical design of the concavepiston base indentation. This indentation is concentric having a basediameter approaching the outside diameter of the piston and it may haveor approach the shape of a spherical indentation. Its depth isdetermined largely by the length of the brake path. The otherpossibility of influencing the brake characteristic consists in theprovision, on the brake shell, of suitable preset breaking ordeformation points in the form of bores, notches, grooves, etc.

Accordingly, it is an object of the invention to provide an improveddeceleration system comprising a cylinder in which a free piston ismovable toward an end thereof and with a brake shell arranged in the endwhich has a portion located in the path of travel of the piston and isconstructed and formed so that it is deformed inwardly by the impact ofthe piston thereagainst.

A further object of the invention is to provide a braking system for afreely movable piston comprising a cylinder in which the piston isfreely movable having a collar formation at one end forming a stop orabutment for a cylindrical plastic deformation member which includes abeveled rim engageable behind an approaching edge of the piston andcooperable with a concave end face of the piston to move inwardly in aformation manner on impact by the piston thereagainst.

A further object of the invention is to provide a deceleration systemwhich is simple in design, rugged in construction and economical tomanufacture.

The various features of novetly which characterize the invention arepointed out with particularity in the claims annexed to and forming apart of this disclosure. For a better understanding of the invention,its operating advantages and specific objects attained by its uses,reference should be had to the accompanying drawing and descriptivematter in which there is illustrated a preferred embodiment of theinvention.

BRIEF DESCRIPTION OF THE DRAWING In the drawing:

FIG. 1 is a partial axial sectional view of an antitank grenade launcherconstructed in accordance with the invention; and

FIG. 2 is a view similar to FIG. 1 showing the deformed brake shellafter the piston has moved to its end position.

GENERAL DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawingin particular, the invention embodied therein comprises, a grenadelauncher cylinder 1 having a collar or inturned flange 2 at its one endwhich forms a stop against which a disposable brake shell or impactreceiving body, generally designated 3, is positioned. The brake shell 3is made of cylindrical tubular form and it is sized to move freelywithin the cylinder 1 and to be arrested or stopped by the collar 2 sothat it cannot be moved out of the cylinder.

In accordance with the invention, the brake shell 3 on the side facing afreely movable piston 4, is chamfered or beveled around a rim 5 so as toform a cooperating surface with a concavely formed end face 8 of a baseportion 7 of the piston 4. A wedge-shaped slot 6 is defined between thebeveled rim 5 of the brake shell 3 and a cylinder wall 1 into whichmoves the rim of the piston 4 at the base portion 7 as the piston movesin the direction of the arrow 10, for example, after the grenadelauncher has been actuated. The impact of the piston 4 against thebraking cylinder 3 causes an inward movement and deformation of the wallof the cylinder 3 to provide a shock absorption of the impact of thepiston and a dissipation of the energy of the shock of braking. Theconstruction of the body shell 3 shown in FIG. 1 includes a plurality ofopenings 9 forming preset deformation points or weakened areas.

In the end position shown in FIG. 2, the shell 3 is shown in plasticdeformation with the piston 4 being located almost to the inner end ofthe collar 2.

While a specific embodiment of the invention has been shown anddescribed in detail to illustrate the application of the principles ofthe invention, it will be understood that the invention may be embodiedotherwise without departing from such principles.

What is claimed is:

l. A deceleration system for high acceleration operated free pistons,comprising a cylinder, a free piston movable in said cylinder, a collarformed on said cylinder adjacent one end, a disposable brake shell of aplastically deformable material located within said cylinder and securedagainst ejection by said collar, said piston having a piston base facingtoward said brake shell with a concave indentation, said shell having anend engageable within said concave indentation of said piston base andbeing deformable inwardly within said base upon impact of said pistonagainst said shell to absorb the impact shock.

2. A deceleration system, according to claim 1, wherein said brake shellis provided with a chamfered rim forming a wedge-shaped annular slotbetween said rim and said cylinder.

3. A deceleration deceleration system for high acceleration operatedfree pistons, comprising a cylinder, a free piston movable in saidcylinder, a collar formed on said cylinder adjacent one end, a brakeshell of deformable plastic material located within said cylinder andsecured against ejection by said collar, said piston having a pistonbase facing toward said brake shell with a concave indentation, saidshell having an end engageable within said concave indentation of saidpiston base and being deformable within said base upon impact of saidpiston against said shell to absorb the impact shock, said brake shellbeing provided with a chamfered rim forming a wedge-shaped annular slotbetween said rim and said cylinder, said brake shell also havingweakened areas to cause the walls thereof to collapse and move aroundthe surface of the concave end portion of said piston.

4. A deceleration system for a recoilless weapon, comprising a cylinder,a free piston movable in said cylinder, and a plastically deformable anddisposable brake shell secured against movement beyond a fixed locationwithin said cylinder located in the path of travel of said piston, saidpiston having an end facing said shell with a concentric concave recessextending substantially over its whole cross section, said shell havinga peripheral portion facing said piston of a size to engage within therecess of said piston when it is moved toward said brake shell so as tobe deformed inwardly by the curvature of the piston recess by the impactof the piston thereagainst to collapse its wall inwardly and to causeits plastic deformation while it stops the movement of said piston.

1. A deceleration system for high acceleration operated free pistons,comprising a cylinder, a free piston movable in said cylinder, a collarformed on said cylinder adjacent one end, a disposable brake shell of aplastically deformable material located within said cylinder and securedagainst ejection by said collar, said piston having a piston base facingtoward said brake shell with a concave indentation, said shell having anend engageable within said concave indentation of said piston base andbeing deformable inwardly within said base upon impact of said pistonagainst said shell to absorb the impact shock.
 2. A deceleration system,according to claim 1, wherein said brake shell is provided with achamfered rim forming a wedge-shaped annular slot between said rim andsaid cylinder.
 3. A deceleration deceleration system for highacceleration operated free pistons, comprising a cylinder, a free pistonmovable in said cylinder, a collar formed on said cylinder adjacent oneend, a brake shell of deformable plastic material located within saidcylinder and secured against ejection by said collar, said piston havinga piston base facing toward said brake shell with a concave indentation,said shell having an end engageable within said concave indentation ofsaid piston base and being deformable within said base upon impact ofsaid piston against said shell to absorb the impact shock, said brakeshell being provided with a chamfered rim forming a wedge-shaped annularslot between said rim and said cylinder, said brake shell also havingweakened areas to cause the walls thereof to collapse and move aroundthe surface of the concave end portion of said piston.
 4. A decelerationsystem for a recoilless weapon, comprising a cylinder, a free pistonmovable in said cylinder, and a plastically deformable and disposablebrake shell secured against movement beyond a fixed locatiOn within saidcylinder located in the path of travel of said piston, said pistonhaving an end facing said shell with a concentric concave recessextending substantially over its whole cross section, said shell havinga peripheral portion facing said piston of a size to engage within therecess of said piston when it is moved toward said brake shell so as tobe deformed inwardly by the curvature of the piston recess by the impactof the piston thereagainst to collapse its wall inwardly and to causeits plastic deformation while it stops the movement of said piston.